As known, electrical actuators can be actuated with different methods. They can be actuated continuously through a direct current, so as to have a constantly controlled force in the case of voice coil actuators, and a retention force and a constant actuation time in the case of solenoid actuators. They can be actuated by a pulse width modulation (PWM) signal. In actuation methods with PWM, the actuator is actuated with a fixed high frequency guide signal and the duration of the pulses is varied to control the actuation force of the actuator or its retention force. If the response time of the actuator is high compared to the frequency of the PWM signal, the response of the actuator is that of dampening the signal so as to give a similar response to that which can be obtained with a direct current signal modifier. Another actuation method is similar to the one used in the operation of electroinjectors, in which the actuator is actuated by a single pulse of variable duration to control the opening time of the injector.